Improved Damage Detection for Beam-type Structures using a Uniform Load Surface

A combined analytical and experimental study is conducted to develop efficient and effective damage detection techniques for beam-type structures. Unlike many other vibration-based damage detection methods, in which the mode shapes are often chosen to retrieve damage information, the uniform load surface (ULS) is employed in this study due to its less sensitivity to ambient noise. In combination with the ULS, two new damage detection algorithms, i.e., the generalized fractal dimension (GFD) and simplified gapped-smoothing (SGS) methods, are proposed. The GFD method is developed by modifying the conventional definition of fractal dimension. By using a moving window, the GFD of ULS can be obtained for each sampling point, and due to the irregularity of ULS introduced by the damage, a peak exists on the GFD curve indicating the location of the damage. Not only does such a peak at the GFD curve locate the damage, but also it reveals the relative size of the damage. The SGS method is also proposed to take advantage of the simple deformation shape of ULS. Both methods are then applied to the ULS of cracked and delaminated beams obtained analytically, from which the damage location and size are determined successfully. Based on the experimentally measured curvature mode shapes, both the GFD and SGS methods are further applied to detect three different types of damage in carbon/epoxy composite beams. The successful detection of damage in the composite beams demonstrates that the new techniques developed in this study can be used efficiently and effectively in damage identification and health monitoring of beam-type structures.

[1]  Ahmet E. Aktan,et al.  Application of Modal Flexibility and Its Derivatives in Structural Identification , 1998 .

[2]  Pizhong Qiao,et al.  Vibration of beams with arbitrary discontinuities and boundary conditions , 2007 .

[3]  Bor-Tsuen Wang,et al.  Feasibility analysis of using piezoceramic transducers for cantilever beam modal testing , 1997 .

[4]  Leontios J. Hadjileontiadis,et al.  Fractal dimension analysis for crack identification in beam structures , 2005 .

[5]  Xiaomin Deng,et al.  Damage detection with spatial wavelets , 1999 .

[6]  E. Peter Carden,et al.  Vibration Based Condition Monitoring: A Review , 2004 .

[7]  S. Quek,et al.  Sensitivity analysis of crack detection in beams by wavelet technique , 2001 .

[8]  B. Mandelbrot.  How Long Is the Coast of Britain? Statistical Self-Similarity and Fractional Dimension , 1967, Science.

[9]  M. J. Katz,et al.  Fractals and the analysis of waveforms. , 1988, Computers in biology and medicine.

[10]  Colin P. Ratcliffe,et al.  Vibration Technique for Locating Delamination in a Composite Beam , 1998 .

[11]  T. Chondros,et al.  Analytical Methods in Rotor Dynamics , 1983 .

[12]  Gangbing Song,et al.  Experimental Damage Identification of Carbon/Epoxy Composite Beams Using Curvature Mode Shapes , 2004 .

[13]  Charles R. Farrar,et al.  A summary review of vibration-based damage identification methods , 1998 .

[14]  S. S. Law,et al.  Damage localization in plate structures from uniform load surface curvature , 2004 .